function xCOMFn = COMFn(x)
xCOMFn = (-12759122123*sin(x(1)) - 14065902578*sin(x(1) + x(2)) +  ...
  1637194622*sin(x(1) + x(2) + x(3)) +  ...
  457593477*sin(x(1) + x(2) + x(3) - x(4)))/34726000000 ...
;